Variable switching point predictive torque control for the three-level neutral point clamped inverter

In this paper the recently introduced control strategy referred as variable switching point predictive torque control (VSP²TC) is employed to control a three-level neutral point clamped (NPC) voltage source inverter driving an induction machine (IM). Based on a predictive torque control (PTC) scheme, the controller aims to reduce the high current and torque ripples that occur. In order to actualize this, a variable switching point is calculated based on an optimization problem formulated to reduce the torque ripple. At this switching point the switches of the inverter change their state to meet all the control objectives, i.e. minimization of the torque ripple, regulation of the torque and the flux magnitude to their references, and balancing of the neutral point potential. Experimental results that verify the performance of the proposed control algorithm are presented.